That’s why the 42-year-old, who probably already has consumed two cases of beer out of the Claret Jug celebrating his improbable British Open victory Sunday, is proof you can reinvent yourself.

“The Big Easy,” you see, had become “The Big Grumpy” in recent years as his golf game faltered and he coped with the challenges presented by his autistic son, Ben.

The same free-spirited Ernie Els I watched tipping back Heinekens with spectators deep into the night at Westchester Country Club after winning the then-named Buick Classic early in his career, was the man who snapped, “Get the [bleep] out of my face,’’ when approached for an interview outside the clubhouse at the Arnold Palmer Invitational two years ago.

The same Ernie Els who frequently bared his soul to reporters as he became the reluctant bridesmaid to so many Tiger Woods wins in majors was the man who angrily marched past reporters without comment after his near-miss at the 2010 U.S. Open at Pebble Beach.

Els later apologized to reporters for his conduct, evidence that, at the core, he is a good guy with good intentions whose attitude simply had gone to the dark side.

Behind the scenes in Els’ march to his second British Open win and fourth career major championship was his change in attitude. Els, in recent months, worked hard at returning to his roots as The Big Easy and last week on the England’s west coast it paid off.

The insightful Graeme McDowell called the Els victory “the return of one of golf’s great champions who’s had a very indifferent three or four years.’’

Els is a champion again because he rediscovered the positive energy he had lost in recent years.

All week, Els, whose last major championship victory had come 10 years ago almost to the day at the 2002 British Open, sounded somewhat clairvoyant about his chances at Lytham — even when few considered him a true contender.

During his victory speech to the fans on the 18th green, Els thanked them for the support all week and added with a wry smile, “I have to ask you: Were you just being nice to me or did you actually believe I could win?’’

After his round Saturday, despite trailing Adam Scott by six shots, Els said, “For some reason, I’ve got some belief this week. I feel something special can happen. Something good is bound to happen, so hopefully it’s tomorrow.’’

These were Els’ words Sunday after the win: “For some reason, I felt something good was going to come out of this. Even if I didn’t win, I was going to feel good about it because of all the work we’ve put in. My game is back to where I feel I can compete.’’

Els rode the power of a positive mind to victory Sunday, far removed from that uncharacteristically agitated guy of the past couple of years.

A huge advocate for autism awareness with his Els for Autism foundation, which has raised millions of dollars, he was also motivated by his love for 9-year-old Ben.

“I made a lot of putts [Sunday] with Ben in mind, because I know Ben’s watching,’’ Els said. “He loves when I hit golf balls. He loves the flight of the ball and the sound. I know he was watching and I wanted to keep him excited, so I made a lot of putts for him.

“It’s amazing, this game, you know?’’ Els went on. “You have a positive feel, you give yourself positive vibes and sometimes positive things happen. I’ve been in such a negative mode for a while, and now that I’m starting to feel more positive, obviously things happen.’’

As obvious as that silver jug on his nightstand that smells like beer.